Retail Food Samples Research Articles

Profiling the Enterobacterales Community Isolated from Retail Foods in England

Enterobacterales include foodborne pathogens of importance to public health and are often targeted in food surveillance programs as both safety and hygiene indicators. Furthermore, Enterobacterales are important in the context of antimicrobial resistance dissemination, also impacting infection treatment efficacy. In this study, the prevalence and characteristics of Enterobacterales in UK retail foods were examined. From 110 retail food samples, 253 Enterobacterales were recovered, with 16S rRNA sequencing revealing a diverse species community, including enteropathogens; the most common were Proteus mirabilis and Escherichia coli (18% each). Antimicrobial resistance was common, with 160/253 (63%) isolates being resistant to at least 1 antimicrobial. Resistance to all tested antimicrobials was observed. Thirteen percent of isolates were multidrug resistant, including 2 isolates each resistant to 8 or 9 of 9 antimicrobials tested. Klebsiella isolates possessed relatively higher levels of antimicrobial resistance to other species. Hafnia, Kluyvera, and Proteus isolates produced significantly higher biofilm biomass than Klebsiella (p = 0.038, 0.028, and 0.042, respectively) or Escherichia (p = 0.001, 0.008, and 0.001, respectively). Simultaneous curli fimbriae and cellulose production was noted in 7% of isolates at 37 °C, but not at 15 °C. This research demonstrates a high diversity of Enterobacterales within UK retail foods, alongside notable antimicrobial resistance phenotypes in enteropathogenic species, highlighting the need for effective surveillance and interventions.

Occurrence and Characteristics of Toxigenic Staphylococcus aureus in Retail Foods in Iran.

Staphylococcus aureus causes various toxigenic and invasive diseases in humans worldwide. This study examined the prevalence, virulence genes, and antibiotic resistance of S. aureus isolates collected from 894 retail food samples in Ardabil, Iran. Staphylococcal cassette chromosome mec (SCCmec), spa, and multilocus sequence typing methods were employed to further investigate the molecular characteristics of methicillin-resistant S. aureus (MRSA) isolates. The results revealed that 11.18% (n = 100) of food samples exhibited contamination with S. aureus (10.50% methicillin-sensitive S. aureus [MSSA] and 0.67% MRSA). Notably, raw minced meat (29.41%), Faloodeh (25%), and Olivier salad (21.42%) emerged as the most frequently contaminated food items. Among the 100 isolates of S. aureus, 94% were characterized as MSSA, with the remaining 6% identified as MRSA. The highest resistance was observed for penicillin (12%). MRSA isolates exhibited significantly higher resistance rates. Seventy-nine percent of the isolates were positive for sea, 14% for seb, 8% for a sec, and 0% for sed enterotoxin-encoding genes. Sixteen percent of isolates harbored two or more staphylococcal enterotoxin genes, simultaneously. Moreover, 97%, 94%, 24%, and 22% of isolates were positive for hla, hld, tst, and pvl virulence-encoding genes, respectively. No isolate was positive for the exfoliative toxins encoding eta and etb genes. MRSA isolates belonged to CC8 (n = 4) and CC22 (n = 2). Isolates in CC8 belonged to lineage ST239-MRSA-III and spa type t030; the isolates in CC22 belonged to ST22-MRSA-IV and spa types t310 and t223. In conclusion, a relatively high proportion of our retail food samples were contaminated with S. aureus. The high incidence of isolates with toxigenic genes raises serious health concerns. Furthermore, the presence of MRSA lineages linked to humans suggests that retail foods may be contaminated with human origin.

Genomic characterization of Pseudomonas spp. on food: implications for spoilage, antimicrobial resistance and human infection

BackgroundPseudomonas species are common on food, but their contribution to the antimicrobial resistance gene (ARG) burden within food or as a source of clinical infection is unknown. Pseudomonas aeruginosa is an opportunistic pathogen responsible for a wide range of infections and is often hard to treat due to intrinsic and acquired ARGs commonly carried by this species. This study aimed to understand the potential role of Pseudomonas on food as a reservoir of ARGs and to assess the presence of potentially clinically significant Pseudomonas aeruginosa strains on food. To achieve this, we assessed the genetic relatedness (using whole genome sequencing) and virulence of food-derived isolates to those collected from humans.ResultsA non-specific culturing approach for Pseudomonas recovered the bacterial genus from 28 of 32 (87.5%) retail food samples, although no P. aeruginosa was identified. The Pseudomonas species recovered were not clinically relevant, contained no ARGs and are likely associated with food spoilage. A specific culture method for P. aeruginosa resulted in the recovery of P. aeruginosa from 14 of 128 (11%) retail food samples; isolates contained between four and seven ARGs each and belonged to 16 sequence types (STs), four of which have been isolated from human infections. Food P. aeruginosa isolates from these STs demonstrated high similarity to human-derived isolates, differing by 41–312 single nucleotide polymorphisms (SNPs). There were diverse P. aeruginosa collected from the same food sample with distinct STs present on some samples and isolates belonging to the same ST differing by 19–67 SNPs. The Galleria mellonella infection model showed that 15 of 16 STs isolated from food displayed virulence between a low-virulence (PAO1) and a high virulence (PA14) control.ConclusionThe most frequent Pseudomonas recovered from food examined in this study carried no ARGs and are more likely to play a role in food spoilage rather than infection. P. aeruginosa isolates likely to be able to cause human infections and with multidrug resistant genotypes are present on a relatively small but still substantial proportions of retail foods examined. Given the frequency of exposure, the potential contribution of food to the burden of P. aeruginosa infections in humans should be evaluated more closely.

A microfluidic genoserotyping strategy for fast and objective identification of common Salmonella serotypes isolated from retail food samples in China

Strict monitoring of Salmonella serotypes is the most effective way to limit the risk of its transmission to humans. In this study, a microfluidic genoserotyping strategy was developed for the rapid and cost-effective detection of 11 common Salmonella serotypes from retail food samples, i.e. Typhimurium, Derby, Indiana, Agona, Rissen, Braenderup, Hadar, Enteritidis, Weltevreden, Meleagridis, and Pomona. The programmable LAMP in the strategy can complete the whole detection process within 40 min and avoid false positive results. The limit of detection was 102 or 103 CFU/mL. Referring to the results of standard culture method, the LAMP-chip was verified with 100% accuracy on testing 688 Salmonella and 22 non-Salmonella strains. This simple, portable and accurate microfluidic genoserotyping strategy is fully adapted to the needs of food regulatory authorities and has wide application prospect in food safety field.

Antimicrobial Resistance and Virulence of Non-Typhoidal Salmonella from Retail Foods Marketed in Bangkok, Thailand.

Nontyphoidal-Salmonella bacteria cause foodborne gastroenteritis that may lead to fatal bacteremia, osteomyelitis, and meningitis if not treated properly. The emergence of multidrug-resistant Salmonella strains is a global public health threat. Regular monitoring of genotypes and phenotypes of Salmonella isolated from humans, animals, foods, and environments is mandatory for effective reduction and control of this food-borne pathogen. In this study, antimicrobial-resistant and virulent genotypes and phenotypes of Salmonella isolated from retail food samples in Bangkok, Thailand, were investigated. From 252 raw food samples, 58 Salmonella strains that belonged only to serotype Enteritidis were isolated. Disc diffusion method showed that all isolates were still sensitive to amikacin and carbapenems. More than 30% of the isolates were resistant to ampicillin, tetracycline, and ciprofloxacin. Twenty isolates resist at least three antibiotic classes. Minimum inhibitory concentration tests showed that 12.07% of the isolates produced extended-spectrum β-Lactamase. Polymerase chain reaction indicated that 32.76, 81.03, 39.66, and 5.17% of the isolates carried blaTEM-1, tetA, sul2, and dfrA7, respectively. All isolates were positive for invasion-associated genes. Effective prevention and control of Salmonella (as well as other food-borne pathogens) is possible by increasing public awareness and applying food hygienic practices. Active and well harmonised “One Health” co-operation is required to effectively control food-borne zoonosis.

Molecular Characterization of Rifampicin-Resistant Staphylococcus aureus Isolates from Retail Foods in China.

This study investigated the molecular characteristics of rifampin-resistant (RIF-R) Staphylococcus aureus isolates recovered from 4300 retail food samples covering most provincial capitals in China, from 2011 to 2016. Of the 1463 S. aureus enrolled, 149 isolates (142 MSSA and 7 MRSA) were identified as rifampicin-resistant, including 20 high-level (MICs ≥ 8 μg/mL) and 129 low-level (MICs between 2 and 4 μg/mL) rifampicin-resistant strains. Most of the RIF-R S. aureus isolates were resistant to more than three antibiotics. The mutations in the rifampicin resistance-determining region of the rpoB gene were studied in all RIF-R strains. All of the strains presented the mutational change 481 His/Asn and five isolates presented an additional mutation, including 477 Asp/Tyr, 527 Ile/Met, and 466 Leu/Ser, respectively. Thirteen STs and twenty-one spa types were represented, in which five MRSA showed non-type SCCmec and the remaining MRSA belonged to SCCmec type IV—where, ST1-t127 was the predominant type from all of the isolates, while ST398-t034 was the predominant type for the MRSA isolates. In this study, we found that the food-related RIF-R S. aureus may have a unique genetic background selection. However, the scenario regarding the presence of RIF-R S. aureus, especially MRSA, in retail food in China is not favorable and warrants public attention.

Occurrence, molecular characterization, and antimicrobial susceptibility of Yersinia enterocolitica isolated from retail food samples in China

Yersinia enterocolitica (Y. enterocolitica) is an important foodborne pathogen that causes gastrointestinal syndromes. The objectives of this study were to examine the incidence of Y. enterocolitica strains in food samples in China and determine their genotypes, in addition to assessing their antimicrobial resistance and pathogenic potential. From June 2015 to June 2016, a total of 1588 food samples were obtained, and 37 (2.33%) were found to be contaminated with Y. enterocolitica. A total of 51 different Y. enterocolitica strains were isolated. All isolates belonged to biotype 1A, and the predominant serotype was O:5. All strains lacked the ail, virF, ystA, and yadA virulence genes, but most strains (>75%) harbored the ymoA, sat, hreP, fepD, and fes genes. Over 85% of the 51 isolated strains were sensitive to tetracycline, trimethoprim/sulfamethoxazole, and chloramphenicol, whereas they were resistant to ampicillin and amoxicillin/clavulanic acid. Furthermore, all the strains were divided into seven clusters according to the results of the enterobacterial repetitive intergenic consensus-polymerase chain reaction. Our research emphasizes, for the first time, that more stringent cold storage methods may increase the risk of Y. enterocolitica contamination.

Heavy Metal Tolerance Trend in Extended-Spectrum β-Lactamase Encoding Strains Recovered from Food Samples.

This study evaluates bacteriological profiles in ready-to-eat (RTE) foods and assesses antibiotic resistance, extended-spectrum β-lactamase (ESBL) production by gram-negative bacteria, and heavy metal tolerance. In total, 436 retail food samples were collected and cultured. The isolates were screened for ESBL production and molecular detection of ESBL-encoding genes. Furthermore, all isolates were evaluated for heavy metal tolerance. From 352 culture-positive samples, 406 g-negative bacteria were identified. Raw food samples were more often contaminated than refined food (84.71% vs. 76.32%). The predominant isolates were Klebsiella pneumoniae (n = 76), Enterobacter cloacae (n = 58), and Escherichia coli (n = 56). Overall, the percentage of ESBL producers was higher in raw food samples, although higher occurrences of ESBL-producing E. coli (p = 0.01) and Pseudomonas aeruginosa (p = 0.02) were observed in processed food samples. However, the prevalence of ESBL-producing Citrobacter freundii in raw food samples was high (p = 0.03). Among the isolates, 55% were blaCTX-M, 26% were blaSHV, and 19% were blaTEM. Notably, heavy metal resistance was highly prevalent in ESBL producers. These findings demonstrate that retail food samples are exposed to contaminants including antibiotics and heavy metals, endangering consumers.

Prevalence of mobile colistin resistance (mcr) genes in extended-spectrum β-lactamase-producing Escherichia coli isolated from retail raw foods in Nha Trang, Vietnam

The aim of the study was to assess the presence of genes in ESBL-producing E. coli (ESBL-Ec) isolated from retail raw food in Nha Trang, Vietnam. A total of 452 food samples comprising chicken (n = 116), pork (n = 112), fish (n = 112) and shrimp (n = 112) collected between 2015 and 2017 were examined for the prevalence of ESBL-Ec. ESBL-Ec were detected in 46.0% (208/452) of retail food samples, particularly in 66.4% (77/116), 55.4% (62/112), 42.0% (47/112) 19.6% (22/112) of chicken, pork, fish and shrimp, respectively. Sixty-five out of the 208 (31.3%) ESBL-Ec isolates were positive for mcr genes including mcr-1, mcr-3 and both mcr-1 and mcr-3 genes in 56/208 (26.9%), 1/208 (0.5%) and 8/208 (3.9%) isolates, respectively. Particularly, there was higher prevalence of mcr-1 in ESBL-Ec isolates from chicken (53.2%, 41/77) in comparison to shrimp (22.7%, 5/22), pork (11.3%, 7/62) and fish (6.4%, 3/47). mcr-3 gene was detected in co-existence with mcr-1 in ESBL-Ec isolates from shrimp (9.1%, 2/22), pork (8.1%, 5/62) and fish (2.1%, 1/47) but not chicken. The 65 mcr-positive ESBL-Ec (mcr-ESBL-Ec) were colistin-resistant with the MICs of 4–8 μg/mL. All mcr-3 gene-positive isolates belonged to group A, whereas phylogenetic group distribution of isolates harboring only mcr-1 was B1 (44.6%), A (28.6%) and D (26.8%). PFGE analysis showed diverse genotypes, although some isolates demonstrated nearly clonal relationships. S1-PFGE and Southern hybridization illustrated that the mcr-1 and mcr-3 genes were located either on chromosomes or on plasmids. However, the types of mcr genes were harbored on different plasmids with varied sizes of 30–390 kb. Besides, the ESBL genes of CTX-M-1 or CTX-M-9 were also detected to be located on plasmids. Noteworthy, co-location of CTX-M-1 with mcr-1 or mcr-3 genes on the same plasmid was identified. The conjugation experiment indicated that the mcr-1 or mcr-3 was horizontally transferable. All mcr-ESBL-Ec isolates were multidrug resistance (resistance to ≥3 antimicrobial classes). Moreover, β-Lactamase-encoding genes of the CTX-M-1 (78.5%), CTX-M-9 (21.5%), TEM (61.5%) groups were found in mcr-ESBL-Ec. The astA gene was detected in 27 (41.5%) mcr-ESBL-Ec isolates demonstrating their potential virulence. In conclusion, mcr-1 and mcr-3 genes existed individually or concurrently in ESBL-Ec isolates recovered from retail raw food in Nha Trang city, which might further complicate the antimicrobial-resistant situation in Vietnam, and is a possible health risk for human.

The prevalence of Clostridioides difficile on farms, in abattoirs and in retail foods in Ireland

An increasing proportion of Clostridioides difficile infections (CDI) are community acquired. This study tested farm, abattoir and retail food samples for C. difficile, using peer reviewed culture and molecular methods. The contamination rate on beef, sheep and broiler farms ranged from 2/30 (7%) to 25/30 (83%) in faeces, soil and water samples, while concentrations ranged from 2.9 log10 cfu/ml to 8.4 log10 cfu/g. The prevalence and associated counts were much lower in abattoir samples. Although 26/60 were C. difficile positive by enrichment and PCR, only 6 samples yielded counts by direct plating (1.1 log10 cfu/cm2 to 5.1 log10 cfu/g). At retail, 9/240 samples were C. difficile positive, including corned beef (1), spinach leaves (2), iceberg lettuce, little gem lettuce, wild rocket, coleslaw, whole milk yogurt and cottage cheese (1 sample each), with counts of up to 6.8 log10 cfu/g. The tcdA, tcdB, cdtA, cdtB, tcdC and tcdR genes were detected in 41%, 99.2%, 33.6%, 32%, 46.7% and 31.1%, respectively, of the 122 C. difficile isolates obtained. It was concluded that although the prevalence of C. difficile decreased along the food chain, retail foods were still heavily contaminated. This pathogen may therefore be foodborne, perhaps necessitating dietary advice for potentially vulnerable patients.

Biofilm-Forming Ability of Pathogenic Bacteria Isolated from Retail Food in Poland

Biofilms have a significant impact on food safety in the food industry. Many foodborne outbreaks have been associated with pathogenic bacterial strains that can form a biofilm. The present study was conducted under the Official Control and Monitoring Program in Poland to examine the ability of pathogenic bacteria collected from retail food samples to form biofilms. Biofilm formation was assessed by qualitative detection of extracellular polymeric substances on Congo red agar, by adherence to glass with the tube method, by the crystal violet biofilm (CV) assay, and by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. A total of 40 isolates from food samples (10 strains each of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Bacillus cereus) were examined. The strains were classified as adherent, slightly adherent, or nonadherent; biofilm production was classified as weak (WBP), moderate (MBP), or strong (SBP); and metabolic activity was classified as weak (WMA), moderate (MMA), or high (HMA). The incubation conditions and time influenced the amount of biofilm formed as well as did the growth medium. In the test tubes with Luria-Bertani broth (LBB), 22.5% of the strains were adherent and 77.5% were slightly adherent. Stronger adhesion was obtained in brain heart infusion (BHI) with 2% sucrose; 60% of the isolates were classified as adherent. With the CV assay with LBB, SBP was noted for 7.5% of the strains after 24 h of incubation and for 37.5% of the strains after 48 h. In BHI plus 2% sucrose, SBP was noted for 42.5 and 37.6% of the strains after 24 and 48 h, respectively. With the MTT assay with LBB, HMA was found for 15% of the strains after 24 h of incubation and for 25% of the strains after 48 h. In BHI plus 2% sucrose, 70 and 85% of the incubated strains were classified as HMA after 24 and 48 h, respectively.

Isolation and Characterization of Non-O157 Shiga Toxin–Producing Escherichia coli in Foods Sold at Retail Markets in China

Non-O157 Shiga toxin-producing Escherichia coli (STEC) strains are significant foodborne pathogens that can cause acute diarrhea in humans. This study was conducted to investigate the contamination by non-O157 STEC in different types of food sold at retail markets in the People's Republic of China and to characterize non-O157 STEC strains. From May 2012 to April 2014, 1,200 retail food samples were collected from markets in 24 cities in China. Forty-four non-O157 isolates were recovered from 43 STEC-positive samples. Of the isolates, 22 and 19 carried the stx1 and stx2 genes, respectively, and 3 harbored both stx1 and stx2. stx1a and stx2a were the most prevalent stx subtypes. Other virulence genes, ent, hlyA, astA, eae, espB, iha, subAB, and tia, were commonly detected. Diverse O serogroups were identified among these isolates. Multilocus sequence typing indicated the high genetic diversity of the isolates. Thirty-two sequence types (STs) were identified among the 44 isolates, with ST383 (9.09%), ST134 (6.82%), and ST91 (6.82%) the most prevalent. Nine new STs were found. The isolates had a high prevalence of resistance to cephalothin, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, nalidixic acid, streptomycin, and chloramphenicol. Twenty isolates (45.45%) were resistant to at least three antibiotics. This study provides updated surveillance data for non-O157 STEC isolates from foods sold at retail markets. Virulent and multidrug-resistant non-O57 STEC strains were isolated from all types of food. Our findings highlight the need for increased monitoring of non-O157 STEC in retail foods.

Prevalence and characterization of Clostridioides difficile isolates from retail food products (vegetables and meats) in Japan

The present study aimed to elucidate the prevalence of Clostridioides difficile in Japanese retail food products. For this purpose, retail food samples (242 fresh vegetables and 266 retail meat samples: 89 chicken meat; 28 chicken liver; 200 pork meat; 24 pig liver; 127 beef meat) were collected from 14 supermarkets between 2015 and 2019. C. difficile was isolated from eight (3.3%) fresh vegetable, six (6.7%) chicken meat, one (3.6%) chicken liver, one (0.5%) pork meat, and two (1.6%) beef meat samples; it was not isolated from pig liver. Of these isolates, 35% were toxigenic. All isolates were typable by PCR ribotyping and were resolved into 12 PCR ribotypes. Among these isolates, ribotype 014, which is distributed worldwide including in Japanese clinical cases, was detected among vegetable isolates. Therefore, although the C. difficile contamination rate in Japanese retail foods was low, these sources can be contaminated and could transmit these bacteria to humans.

Fermented Foods as a Dietary Source of Live Organisms.

The popularity of fermented foods and beverages is due to their enhanced shelf-life, safety, functionality, sensory, and nutritional properties. The latter includes the presence of bioactive molecules, vitamins, and other constituents with increased availability due to the process of fermentation. Many fermented foods also contain live microorganisms that may improve gastrointestinal health and provide other health benefits, including lowering the risk of type two diabetes and cardiovascular diseases. The number of organisms in fermented foods can vary significantly, depending on how products were manufactured and processed, as well as conditions and duration of storage. In this review, we surveyed published studies in which lactic acid and other relevant bacteria were enumerated from the most commonly consumed fermented foods, including cultured dairy products, cheese, fermented sausage, fermented vegetables, soy-fermented foods, and fermented cereal products. Most of the reported data were based on retail food samples, rather than experimentally produced products made on a laboratory scale. Results indicated that many of these fermented foods contained 105−7 lactic acid bacteria per mL or gram, although there was considerable variation based on geographical region and sampling time. In general, cultured dairy products consistently contained higher levels, up to 109/mL or g. Although few specific recommendations and claim legislations for what constitutes a relevant dose exist, the findings from this survey revealed that many fermented foods are a good source of live lactic acid bacteria, including species that reportedly provide human health benefits.

Development of a gold nanoparticle-based universal oligonucleotide microarray for multiplex and low-cost detection of foodborne pathogens

Bacterial foodborne diseases remain major threats to food safety and public health, especially in developing countries. In this study a novel assay, combining gold nanoparticle (GNP)-based multiplex oligonucleotide ligation-PCR and universal oligonucleotide microarray technology, was developed for inexpensive, specific, sensitive, and multiplex detection of eight common foodborne pathogens, including Shigella spp., Campylobacter jejuni, Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, and Vibrio parahaemolyticus. The target fragments of the eight pathogens were enriched by multiplex PCR and subjected to multiplex ligase detection reaction. Ligation products were enriched and labeled with GNPs by universal asymmetric PCR, using excess GNP-conjugated primers. The labeled single-stranded amplicons containing complementary tag sequences were captured by the corresponding tag sequences immobilized on microarrays, followed by silver staining for signal enhancement. Black images of microarray spots were visualized by naked eyes or scanned on a simple flatbed scanner, and quantified. The results indicated that this assay could unambiguously discriminate all eight pathogens in single and multiple infections, with detection sensitivity of 3.3–85CFU/mL for pure cultures. Microarray results of ninety-five artificially contaminated and retail food samples were consistent with traditional culture, biochemical and real-time PCR findings. Therefore, the novel assay has the potential to be used for routine detection due to rapidity, low cost, and high specificity and sensitivity.

Prevalence, antimicrobial resistance and multiple-locus variable-number tandem-repeat analysis profiles of diarrheagenic Escherichia coli isolated from different retail foods

Diarrheagenic E. coli (DEC) isolates were recovered from local retail markets and the Osaka Municipal Central Wholesale Market in Japan. Retail food samples were collected for analysis in Osaka Japan from 2005 to 2008 and consisted of 32 beef, 28 pork, 20 poultry, 136 fish, 66 fruits and vegetables and 51 ready–to-eat (RTE) food samples. A total of 82 DEC strains were recovered from 64 (19%) food samples with the highest prevalence in poultry (100%, 20/20), followed by pork (54%, 15/28), beef (28%, 9/32), fruits and vegetables (12%, 8/66), fish (6.6%, 9/136) and RTE foods (5.9%, 3/51). Most of the strains belonged to E. coli possessing the enteroaggregative E. coli (EAEC) heat-stable enterotoxin 1 (EAST1) gene (EAST1EC; n=62, P<0.0001) and enteropathogenic E. coli (EPEC; n=16, P<0.01), whereas only 1 strain belonged to Shiga toxin-producing E. coli (STEC), 1 to EAEC and 2 to enterotoxigenic E. coli (ETEC) strains. Of the 82 DEC isolates, 22 O and 13H serogroups were detected, including some specific serogroups (O91, O103, O115, O119, O126, and O157) which have been associated with human diarrheal infections. Phylogenetic group A and B1 were predominant among the DEC isolates. Antimicrobial resistance to tetracycline was most common (49%), followed by nalidixic acid (28%), ampicillin (24%), sulfamethoxazole/trimethoprim (20%), and cephalothin (18%). All isolates were susceptible to aztreonam. Of the resistant strains, 44% (22/50) demonstrated resistance to >3 antimicrobial agents. Isolates resistant to >5 antimicrobials were only found in the meat samples, while isolates from the fruits and vegetables as well as RTE foods showed resistance to only 1 or 2 antimicrobial agents. Sixty one percent of EAST1EC, 56% of EPEC and all of the EAEC and ETEC were resistant to at least 1 antimicrobial agent. Multiple-locus variable-number tandem repeat analysis (MLVA) was used in this study for genotyping of DEC. The 82 isolates collected for this study showed 77 distinct MLVA profiles located among 3 branches. The Simpson's Index of Diversity (D) was 99.9% at its highest. The high diversity of these food strains would suggest their originating from a variety of sources and environments. In conclusion, retail food samples in Japan were contaminated with DEC; EAST1EC, a putative DEC, were detected at high rates in poultry, pork and beef. Isolates resistant to >3 antimicrobials were found only in raw meat and fish. Food animals may act as the reservoir for multi-resistant bacteria. Due to the finding that nearly 1/3 of EAST1EC strains were resistant to >3 antimicrobials, additional surveillance for EAST1EC should be initiated.

Can a visual loop-mediated isothermal amplification assay stand out in different detection methods when monitoring Campylobacter jejuni from diverse sources of samples?

Consumption and exposure to Campylobacter-contaminated food are important causes of bacterial diarrhea. This paper reports the development and evaluation of a visual loop-mediated isothermal amplification (LAMP) assay targeting the highly conserved cjaA gene of Campylobacter jejuni (C. jejuni). This assay could be used for specialized detection and primary screening of retail food samples in China. When applied to 475 different samples, PCR (14.9%) and bacterial culture (12.7%) showed lower detection rates than the LAMP, which demonstrated 51 positive (16.6%) with a 100% diagnostic sensitivity to bacterial culture with no targets undetected. When tested with samples that had different cleanliness, the specificity (0.955), accuracy (0.961), positive likelihood ratio (22.417), kappa coefficient (0.844) for retail food samples tested by LAMP were higher than for fecal and environmental samples. Moreover, when tested with food samples that had different C. jejuni carry rates, LAMP was more sensitive in monitoring raw pork meat samples-the specificity (0.958), accuracy (0.958), and positive likelihood ratio (23.600) were higher than for chicken samples compared with a bacterial culture. The LAMP test enables the cost-effective detection of C. jejuni in food samples in 40 min, and it can also function as a primary screening approach or a complementary method in large-scale and on-site assays of food.

Genotypic characterization of quinolone resistant-Escherichia coli isolates from retail food in Morocco

ABSTRACTThis study was conducted to assess the retail food as a possible vehicle for antimicrobial resistant, particularly quinolones resistant and pathogenic Escherichia coli. We determined the prevalence and characteristics of nalidixic acid (Nal) resistant E. coli isolates from diverse retail food samples. In all, 70 (28%) of 250 E. coli isolates studied were Nal-resistant E. coli and 91% of these were multi-drug resistant. Plasmid mediated quinolone resistance genes were identified in 32 isolates, including aac(6′)-Ib-cr (n = 16), qnrS1 (n = 11) and qnrB19 (n = 7). Mutations in gyr A and par C genes were detected among 80% of the isolates, and the isolates showed substitution Ser83-Leu and Asp87-Asn in gyrA and Ser80-Ile in parC. In addition, three different gene cassettes were identified (aadA1, aadA7, aac(3)-Id) in 18%. Virulence-associated genes stx1, eae, sfa, hlyA and stx2 were found in six (8%), three (4%), two (3%), three (4%) and three (4%) isolates, respectively. E. coli isolates of phylogenetic group A were dominant (64%, 45/70). Pulsed field gel electrophoresis revealed none epidemiological relationship between these isolates. The results of this work report the higher frequency of Nal-resistant E. coli isolates from Moroccan retail food samples including MDR and pathogenic isolates.

Prevalence, genetic diversity and antimicrobial susceptibility of Campylobacter jejuni isolated from retail food in China

The aim of this study was to determine the prevalence, antimicrobial resistance and molecular epidemiology of Campylobacter jejuni isolated from retail food samples in China and assess the potential risk to consumer' health. A total of 34 strains of C. jejuni isolated from 1798 retail food samples in China were identified using conventional methods and duplex PCR aimed 16S and hipo genes. There are 59 positive samples by conventional method, and the prevalence of C. jejuni was 3.30% (59/1798). Using flaA RFLP-PCR (flaA Restriction Fragment Length Polymorphism) typing with a relative similarity coefficient of 0.81, the 34 isolates and 1 reference strains were grouped into 4 clusters and 2 singletons. Antibiotic resistance profiles determined using the disk diffusion method showed that a high proportion of C. jejuni isolates were resistant to the tested antibiotics, particularly for ciprofloxacin (88.5%) and nalidixic acid (88.5%). Most isolates were multidrug resistant, with 20 strains showing resistance to 5–8 antibiotics and 2 strains showing resistance to 9 antibiotics. Moreover, analysis using MAMA-PCR to determine the gyrA mutation status (C257T) indicated that approximately 30 strains had mutations, and these findings were consistent with disk diffusion assay results. Examination for the presence of 11putative virulence genes showed that the majority of these genes were detected in all C. jejuni strains. There was no direct evidence to suggest a connection between antibiotic resistance and virulence genes. This study is the first to explore the potential sources of C. jejuni contamination in retail foods in China and provide comprehensive surveillance on its incidence in retail foods. These data will ensure more accurate treatment of human campylobacteriosis using effective antibiotics.

ARCOBACTER SPECIES AND THEIR RISKS IN SOME MEAT AND FISH WITH A SODIUM ACETATE AND SODIUM CHLORIDE INTERVENTION

A surveillance study of retail foods was conducted in Assiut, Egypt to assess the presence of Arcobacter spp. on retail food samples. A total of 75 fresh samples of beef, minced beef, and fish (Oreochromis niloticus), 25 each were purchased from fresh markets in Assiut city and tested for Arcobacter spp. The survey was carried out by differential culture, phenotying and genotyping. A total 35 (47 %) of samples was contaminated with Arcobacer spp. Beef was the most contaminated 13(52%) followed by minced beef 12(48%) then fish 10 (40%). By genotyping using PCR, only a total 11 (15%) of samples harbor Arcobacter spp. Five (20%) of beef, 2 (8%) of minced beef and 4 (16%) of fish were contaminated with Arcobacter spp. When the isolates were confirmed by genus-based PCR, A. butzleri, A. skirrowii and A. cryaerophilus were present in a total 4 (5%), 5 (7%) and 2 (3%) of examined retail foods. The highest A. butzleri contamination level was in beef samples 2 (8%). A. cryaerophilus, A. skirrowii and A. butzleri were examined for their susceptibilities to antibiotics using a disk-diffusion method. All were resistant to Lincomycin, Vancomycin, Tetracycline. Cloxacillin, Cephradine, Novobiocin and Oxacillin but susceptible to Gentamycin and Neomycin. With the exception of A. cryaerophilus the tested Arcobacters were susceptible to Ciprofloxacillin. The effect of sodium acetate (SA) and sodium chloride (SC) on growth inhibition of Arcobacter spp. was investigated by determining the minimum inhibitory concentration (MIC) and the minimum lethal concentration (MLC). Sodium acetate provided overall greater inhibition in comparison with (SC). The MLCs were 6% and 9% for of (SA) and (SC), respectively. The corresponding MIC values were 4% and 6%, respectively. The combined effect of (3% SC) and SA at different concentrations (0.01 - 0.05%) were tested against A. butzleri in the growth medium. A significant (P ˂ 0 .05) reduction level of A. butzleri cells was obtained by the combination of 3% (SC) and 0.04 or 0.05% (SA). The greatest reduction (2.7 log)was achieved by the combined effect of 3% (SC) and 0.05% (SA). In minced beef model, (3% SC + 0.05% SA) mixture took 12 h to produce 1 log reduction in the initial A. butzleri count and the reduction was proximate at 24h period. The difference in A. butzleri count between treatment and control samples was significant (P ˂ 0.05). The present study identified beef and minced beef as important food sources of A. butzleri which pose a threat for human health. Also it cleared that fish at retail has been detected to be a further food matrix for A. butzleri. Regarding the enteropathogen A. butzleri, (3% SC + 0.05% SA) mixture can improve the safety of minced meat under refrigerate storage. This study also shows that Gentamycin would be drugs of choice and Neomycin as alternative for treatment of Arcobacter borne gastrointestinal infection in this geographical area. The public health significance of Arcobacter spp. and the control measures were also discussed.